In a hitherto conventional method for mechanical mounting of vehicle wheels, the rim is held firmly in a horizontal position by means of a clamping device, with the rim dish facing up- or downwards. The pneumatic tire is placed on the rim at an angle and pushed thereonto until the lower tire bead is forced with a lower portion into the rim well base, while it projects with its upper portion over the upper rim flange. Then fitting tools are lowered onto the tire and the rim from above and press the tire sidewall downwards into the depth of the rim well base. By rotating the fitting tools about the axis of rotation of the rim, the tire bead is then drawn continuously over the upper rim flange. This known method has the disadvantage that it stresses the tire very severely during mounting. In the case of tires which are difficult to mount, problems may also arise due to the tire bead not remaining sufficiently in the well base during the mounting procedure as a result of the inherent rigidity of the tire. At the end of the fitting movement, the free length of the tire bead is then insufficient for it to pass over the rim flange, such that considerable shear forces arise as the fitting tools rotate further. Additional technical problems also arise with the known method from the requirement for a high level of flexibility with regard to the different combinations of rim and pneumatic tire to be handled, and from the requirement for short machine cycle times.
With tires which are very easy to mount, the two tire beads are fitted in the manner described above jointly in a single operation. If, on the other hand, it is necessary to mount the tire beads separately, the fitting tool is subject to conflicting requirements. To fit the first bead, the tool has to be of particularly narrow construction, so that it can be inserted without difficulty between the rim flange and the upper bead. When it is raised after mounting of the first bead, it must not get caught on the tire. For mounting of the second bead, on the other hand, it is desirable to have a wide fitting tool available, since low tires with a high level of inherent rigidity have a tendency to come off a narrow fitting roller, such that the tool becomes wedged between rim flange and tire bead as the mounting procedure progresses.
Tire mounting design is also subject to additional technical problems resulting from the requirement for a high level of flexibility with regard to the combinations of rim and pneumatic tire to be handled, and from the requirement for short machine cycle times.
An installation for mounting pneumatic tires on well base rims is known from U.S. Pat. No. 4,621,671, in which the rims are conveyed on pallets with predetermined spacing along a conveyor to two tire mounting devices located one behind the other. The pneumatic tires are transferred into the conveyor via a tire soaping station upstream of the first tire-mounting device, in such a way that in each case one tire arrives in front of one rim in the conveying direction and is placed aslant onto the next rim. As it passes through the first mounting device, the pneumatic tire is then pressed onto the rim by means of a roller rolling thereover, in such a way that the lower tire bead is slipped over the rim flange. Then, in the second mounting station the upper bead of the preliminarily mounted tire is mounted by means of conventional mounting tools passed along the rim flange. This known method has the disadvantage that, during mounting of the lower bead, the pneumatic tire may move in an uncontrolled manner as a result of the roller moving thereover and be damaged thereby. Moreover, each change of tire type or rim type requires complex adjustment of the tire delivery system and of mounting roller movement.
A further apparatus for mounting a pneumatic tire on a rim is known from WO99/42309, said apparatus comprising a robot with an articulated arm movable in three directions, said arm being movable along a movement path which may be selected from a large number of programmable, predetermined movement paths stored in the memory of a central unit. The articulated arm bears at its free end a mounting tool which is moved along the rim edge to mount a tire bead. The robot comprises sensors, which measure the load on the articulated arm, and the robot's control program includes a monitoring function, which stops movement of the tool if the load exceeds a predetermined value. The apparatus additionally comprises a clamping device, which forces the tire into a tilted position prior to mounting and prevents rotation of the tire on the rim.